Description:
------------
If the MYSQLI_CURSOR_TYPE_READ_ONLY option is active on a mysqli statement, mysqlnd_fetch_stmt_row_cursor is selected as row fetch method.

mysqlnd_fetch_stmt_row_cursor expects a MYSQLND_STMT passed as "param" parameter.  mysqlnd_res::fetch_into passes a zval as this parameter, which yields to a crash.

Test script:
---------------
<?php
$link1=mysqli_connect(....);
$SQL="SELECT 1";
$stmt=$link1->prepare($SQL);
$stmt->attr_set(MYSQLI_STMT_ATTR_CURSOR_TYPE, MYSQLI_CURSOR_TYPE_READ_ONLY);
$stmt->execute();
$res = $stmt->get_result();
while($res->fetch_row());
?>


Expected result:
----------------
No segfault

Actual result:
--------------
Segfault in
1022                    SET_CLIENT_ERROR(*stmt->conn->error_info, CR_COMMANDS_OUT_OF_SYNC, UNKNOWN_SQLSTATE,

mysqlnd_fetch_stmt_row_cursor at ext/mysqlnd/mysqlnd_ps.c:1022
php_mysqlnd_res_fetch_into_pub at ext/mysqlnd/mysqlnd_result.c:1823